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Battery light comes on under acceleration

warrenpfo

Well-Known Member
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Jul 21, 2010
Messages
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Here is one I have never had before not can I find anything about it on the web. (I will keep looking) On my short trip to work this morning I noticed the battery light had come on and then when releasing my foot off the accelerator to take a corner I noticed the light went off and then back on when accelerating out the corner again.

I got to the car park and with the car idling there is no battery light but under acceleration it pop back on again. I whipped the book out and it says that the light indicated battery discharge.

Is this Toyotas way of telling us that the battery is not getting charge i.e. the alternator has a problem or that the batteries are at the end of their life or that they are in fact discharging instead of charging?

Any bright ideas welcome and ill check the alternator belt and get the batteries checked at lunch time.

EDIT - It would seem I need to check the batteries with the engine off it should give me 12v and with the engine on close to 14v if not then the alternator is on its way out.
 
The voltage with the engine running will vary depending on demand and battery charge state. Also, you need to let the battery voltage settle after you switch the engine off as it will stay high for a while slowly falling back to normal as the surface charge dissipates. So give it a while, or put the headlights and blower on for a bit to remove the surface charge but don't blame me if you can't start it after because the batteries aren't charged :)

What you should see is 12.4-12.8 with the engine off for charged batteries and about 13.6-14.4 with it running.
 
Right.

I have 12.4V on the batteries and 13.4v when idle going up to 16v+ when under acceleration. The battery light comes on around 2000rmp or 16v+ from the alternator.

Any other suggestions welcome.
 
Hi Warren,

16v sounds very high. You probably have a problem with the regulator that controls the voltage coming off the alternator. I think you should get it seen to as soon as possible as you could damage the batteries (and possibly electronic components) with that sort of voltage. In this instance it seems that the warning light is warning of over charging rather than not charging.
 
Agreed, I boiled two batteries like that. I was hitting 18v at one point. Try to take some of the load when running by using lights, blowers etc and see if the light still comes on. Alternator rebuild on the cards I think. IIRC mine went on and off in the same way as yours when driving.

Don't be long sorting it.

Chris
 
Thanks Chris Ill give running with everything electrical on and see what happens.

I have sent Karl an email asking for a replacment alternator cost as well as Simon at Toyota for parts cost so I can get the job done this weekend.

Whilst im there I also thought of doing the brushes...anything else?

All this and I am selling her as soon as I get my ass into gear.
 
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I would think brushes would be fine. You only need the reg. I bought one recently for mine from the states - £32. Unfortunately like a donkey, I went and broke it. You don't always need to swap the whole thing. We have a local place who turns them round in a day for about £60 if it's just a part needed. Try a local Motor Factor and see if they use some one. Usually a test and opinion is free.

Chris
 
Simon has come back with a cost of £110 for the regulator and out of interest a new Alternator is only £230 which i thought was not too bad.

Ill give it a test on the way home tonight and then place the order tomorrow.
 
Warren, did you ask simon about the exchange? 'Though at £230, that might be it?

Sent from my GT-P7510 using Tapatalk 2
 
Crispin you have lost me on the exchange rate....I thought Simon was local in the UK at one of the dealerships. I take it from your comments he is based abroad. The screen print he sent me was in UK pounds.

The plot thickens this morning as I went to start the cruiser and she was dead. Last night I did what Chris recommended and as soon as the battery light came on I switched the lights, radio and heat seater on and it went off and stayed off until I got home.

My thinking is that I may have either drained the batteries on the trip home and they did not recharge prior to me switching off .

The problem I have is that I need to fix the problem but in the most cost effective way as I am selling her. I think ill pop too get the batteries tested at lunch, and depending on what they say replace them and/or order the part from Simon.
 
When the regulator goes, you get an open circuit to earth and the battery will drain straight through. It's not that it is't charged - it is. But it drains very quickly which is what hammers them. Overcharging and deep cycling. That's why I said hurry up and get it fixed mate

Chris
 
ha ha. Sorry, Simon is very much UK (He's across the road from me). They do an exchange on alternators. I did it with my 120's. You take the recon one from him (It has a Toyota recon warrenty on it) You pay for the new one and a deposit. When you bring your one back, you get your deposit back. I really cannot remember what mine cost but I do remember a new alternator was £400ish.

If he quoted you £230 then that might already be the recon-exchange thing.

Hopefully the reason your LC is dead this morning is just because the batteries gave up or it popped the alternator fuse and nothing more.

If it helps, I could collect the stuff for you and meet you somewhere with it?
 
Thanks, I have put the order in for a new regulator and await the best method for payment from Simon.

Many thanks for the offer of collection, but its a small part so happy to pay postage and get it for the weekend (fingers crossed).

Will keep you posted and do a write up on how too. For now I will pop the batteries on charge and not drive the truck.
 
Chris said:
When the regulator goes, you get an open circuit to earth and the battery will drain straight through. It's not that it is't charged - it is. But it drains very quickly which is what hammers them. Overcharging and deep cycling. That's why I said hurry up and get it fixed mate

Chris

When I am on a trip in the back of beyond I disconnect the batteries overnight to eliminate the risk of any overnight drain. Sorry didnt think to suggest yesterday.
 
Related to the topic, if I was to put the batteries on charge is it possible to charge both be it series or parallel with a Ctek charger or would it just confuse the "intelligent" charger.
 
Best to do one at a time. Reason is that one battery might have a problem with charging and the charger would react to it while the other battery might be perfectly fine.

If you had to, parallel only.
 
Right so I managed to get home at 6 from work so thought I would tackle removing the alternator.

Well it was a 20min job and I was/am doubting if I have removed the right thing but I can’t be that stupid....or can I?

Any way my next concern is that I have ordered a new Voltage Regulator from Toyota only to remove the part and now I am not sure it is a Toyota part but rather another alternator as it has the following sticker on it rather than a Toyota one.

http://www.flickr.com/photos/warrenpfotenhauer/7748063384/
 
That certainly is the alternator but it could just be a toyota one reconned by someone else.
The best would be to open it and compare regulators. If the one you bought is incorrect, so long as it is unused, Simon will (normally) take it back.
 
I take it from that, that you didn't get your alternator tested as I suggested? Hopefully it's only the regulator. There can be other things go wrong in there. If you have somewhere local, I would get it tested before you stick it back in. I appreciate that not everyone as access to services like these, but you'd be surprised what people are offering. It's always worth tracking down specialists in your area. Usually third unit, under the arches, Staples Corner :lol: :lol:


Chris
 
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